Merging coverage reports

I've been looking for code coverage for my native C++ projects and finally came across this great project. Easy to setup and I can get some useful information already.

I'm now trying to set it up with my TeamCity testing server for continuous integration. My plan was to merge the output from each of my different unit tests into one large coverage file. After testing this though, I see that I get output separated by executable.
What I'm looking for is each file coverage to be merged together so I can see if everything is covered between the different unit tests.

I created a similar sample application and I can see now what you mean. What I was hoping for though was more a single list of all the files, not broken down by executable. Suppose we extend so there are two main functions:

Now with the same OpenCppCoverage commands I get one report with two sections, one for each executable. Each section then contains the main for the project, plus the shared header, with coverage mixed from both runs. This is good, but I'd like to see one section
with all 3 files, rather than 2 sections each with 2 files, one which is shared between the two. Does this make sense?

In a larger scale, I have unit test A, unit test B. They test moduleA and moduleB respectively. But module A and module B each use shared library C which has a few files in it.
Now if I chain everything together, and look at the results, it is true that file C shows the aggregated coverage from Unit Test A and Unit Test B regardless of which section I look in, but to find my results I have to go into each section. I look at Unit Test
A section and see module A and library C, but then I have to look at Unit Test B section to see module B. And then I see library C a second time.

I'm finding this hard to describe, but basically I'm looking for an option to see one result section with every file from every executable all mixed together and aggregated together.

It will create a cobertura report in XML format and a classic HTML report.
You can then create a small script that parses the XML and generates the aggregation you need on HTML format for example.

If you want to have the details of the coverage for a file, you can add a link to the generated HTML report. The format is quite simple: HtmlReportFolder/Modules/ModuleName/FileName.html. Both
ModuleName and Filename are available in the XML.